From what I understood, you won’t need to be at the interview and you don’t need to file any forms. I am also marriage based green card holder, and I only filled out my own n-400 form, my husband didn’t fill out anything. But we live together and generally do everything together, so he will definitely be next to me during my interview (if they won’t allow him inside the building, he’ll be waiting in the car).
What’s your field office?